Strainer bag construction



Dec. 31, 1968 E. A. SMITH ETAL 3,419,151

STRAINER BAG CONSTRUCTION Filed Nov. 15, 1966 Sheet SLU RRY INVENTORS E D WA D A. 5M ITH ARTHUR C WROTNOWSKI ATTORNEYS Dec. 31, 1968 E. A. SMITH ETAL STRAINER BAG CONSTRUCTION Sheet 2 of 4 Filed Nov. 15. 1968 W oM ATTORNEYS Dec. 31, 1968 E. A. SMITH ETAL 3,419Ql51 STRAINER BAG CONSTRUCTION Filed Nov. 15, 1966 Sheet .3 of 4 THREAD USED B67 NYLON p.51. BURST l l l I I l l l l o 1 a 9|Ol| lalsmlsl's |7|e|s STITCHES/INCH VERTICAL sEAM STRENGTH TEST FIG.IO

RS. I. BURsT I I I BOTTOM SHAPE PRESSURE TEST FIG.H

INVENTORS EDWARD A. SMITH ARTHUR C.WRO TNOW$K| 4m zn/m.

ATTORNEYS Dec. 31, 1968 Filed Nov. 15, 1966 PS. I.

INITIAL BAG CIRC.

E. A. SMITH ETAL STRAINER BAG CONSTRUCTION Sheet MUSLiN CIRC.

(BREAK uNE) FLAT H CIRC. 22

{3. I S INCHES INVENTORS EDWARD A. 5M ITH ARTHUR c. WROTNOWSKI BY A TTOR/VEYS United States Patent 3,419,151 STRAINER BAG CONSTRUCTION Edward A. Smith, Glenville, and Arthur C. Wrotnowski,

Greenwich, 'Conn., assignors to American Felt Company, Glenville, Conn., a corporation of Massachusetts Filed Nov. 15, 1966, Ser. No. 594,619 1 Claim. (Cl. 210460) ABSTRACT OF THE DISCLOSURE A strainer bag made of fabricated flat felt, the bag having an open end and a rounded bottom to provide a substantially stress-free strainer bag when it is operating as a strainer. Also the bag may have an outer retainer jacket which is larger than the original circumference of the bag.

This invention relates to removable strainer bags and particularly those having an arcuate-like or rounded bottom end, the strainer media being of mechanically interlocked felt.

In the prior art, strainer bags have been rectangularly shaped with different configurations, such as being neckedin at the top and being made of a plurality of pieces. Usually, the bags have been tied onto the feed pipe. The bags must be strong enough so that optimum hydrostatic pressure can be used so as to provide optimum straining cycles. Also, bag combinations are needed to provide such cycles. Prior arrangements and bags have required frequent and expensive replacement and have not been satisfactory.-

One of the objects of the present invention is to provide a strainer bag of optimum shape or strength characteristics.

A further object of the invention is to provide a strainer bag having restraining means of selected dimensions for optimum efliciency and construction.

In one aspect of the invention, the strainer bag is made of one piece of felt which can be fabricated flat with a rounded-like bottom end, the rounded or curved bottom profile having chords located on a bias relative to the sides. The seams preferably are overlapped and the vertical seam extends to the bottom of the bottom end or bisects the angle thereof. The biased bottom end portions can have a slightly convex curve therein. The seams preferably are sewn with a plurality of rows of threads.

The felt preferably is composed of mechanically interlocked man-made fibers. The fibers may be of nylon, rayon, polypropylene, the polyester sold under the trademark Dacron of Du Pont or the acrylic fiber sold under the trademark Orion of Du Pont. Natural fibers also could be used. They can be chosen to produce a series of bags of felt calibrated as described in copending application Ser. No. 637,310, filed Nov. 2, 1966, in order to provide optimum strainer media which can separate or classify particles effective in the to 200 micron range. The bags can have attachment means such as described in copending application Ser. No. 599,661, filed Nov. 15, 1966.

In a further aspect, the felt bag can be enclosed in a muslin bag of selected dimensions or can be put into a wire basket. The bags can be used in conjunction with pressure vessels.

These and other objects, advantages and features of the invention will become apparent from the following description and drawings which are merely exemplary.

In the drawings:

FIG. 1 shows a piece of felt for producing the bag of the present invention;

FIG. 2 is a fragmentary view of the upper portion of the felt bag with the side seam completed;

3,419,151 Patented Dec. 31, 1968 FIG. 3 shows the felt of FIG. 2 with the vertical seam arranged to extend to the center of the rounded bottom end;

FIG. 4 is similar to FIG. 3 except that the vertical seam is at the side;

FIG. 5 shows the strainer bag in place on a holder and illustrates fluid flowing therefrom;

FIG. 6 shows another arrangement of the strainer bag with an outer muslin holder;

FIG. 7 shows the strainer bag within a wire basket and vessel;

FIG. 8 shows the cloth of FIG. 1 cut to form the arrangement of FIG. 3;

FIG. 9 shows one form of attachment means at the upper end of the bag;

FIG. 10 is a graph showing the relation of burst strength and seams;

FIG. 11 is a graph showing the relation of burst strength to the angle between a line or chord forming the lower portion of the rounded bottom end and the intersection of the bottom end with the sides;

FIG. 12 is a fragmentary view of a further embodiment; and

FIG. 13 is a graph showing the relation between the bursting strength and the relation of initial sizes of the bag and the muslin jacket therefor.

Referring to FIG. 1, the bag preferably is made of a single piece 10 of mechanically locked or needled felt. The felt also could have a woven insert as described in the patent to Gates, No. 2,588,228.

The preferred form is shown in FIG. 3 wherein the piece of felt is cut as shown in FIG. 8. Vertical seam 11 extends from the top or open end of the bag to the intersection 12 of the chords or edges 13 of the rounded bottom end 14 of the bag. The edges 13 have sewn seams. The vertical seam 15 also could be made at the side as seen in FIG. 4.

By making the bag of a single piece, instead of two pieces, the bottom is rounded to produce a stress-free bag utilizing of the inherent strength of the material from which it is made. If the bottom is made on the bias with a slight convex curve, a stress-free bag is produced. It was found that if the angle between the sides and a chord to the bottom is made between 32 and 45, the optimum limit pressure results were attained as can be seen in FIG. 11.

The seams are overlapped and a plurality of rows of stitches employed. Merely by way of example, the distance between rows of stitches and distance between rows can be made:

TABLE I 2 rows 3 rows The thread can be the same as the material of the bag.

In use, the bag can be suspended from a holding plate 14 which has a fluid supply pipe 12 thereto. The upper open end 16 can have a hem 17 (FIGS. 5, 9) with a flexible hoop 18 sewn therein. The holding plate 14 has a flange or ledge 19 for receiving the open end of the bag in assembled relation. Details of the holding means are shown in copending application Ser. No. 599,661, filed Nov. 15, 1966.

By use of the rounded-like bottom, the liquid passing through the strainer bag is guided to form a central stream 20 as seen in FIG. 5. This will prevent undesirable splashing and facilitate the collection point. If the end is square, the liquid will be irregular in its flow and will tend to flow from the corners which is not desirable.

An extension 25 (FIG. 12.) can be used further to concentrate or direct flow from the bottom or center of the strainer.

In a further arrangement, a muslin outer container or restrainer can be used as seen in FIG. 9. The muslin 21 can be used to enclosed bag 22 and support it at its top end as seen in FIG. 9.

As pressure is increased, the felt bag will tend to expand. The muslin tends to restrain such expansion so that a greater pressure can be used, such being possible up to the point the muslin bursts.

As an example and referring to FIG. 13, at 16 p.s.i., the muslin should be 1% larger and at 22 p.s.i. 2%" larger, 16 p.s.i. and 22 p.s.i. being the burst pressure when the muslin is made 1%" and 2%" larger than the felt bag. Thus, with a 44 x 36 count 1 ounce per square yard muslin, it should have a circumference of 14 inches, while the bag circumference should be 11% inches in order to reach a 22 psi. break point.

In the form shown in FIG. 6, the strainer is surrounded by a vessel 23 having an outlet 24.

In a still further form, the strainer 26 (FIG. 7) can be held in a wire basket 27 which is supported on ledge 28 of the walls 29 of vessel 30.

The strainer described herein also could be placed in various types of pressure vessels (not shown).

It is to be understood that the bottom edges could follow a chord without substantial curvature and the term rounded bottom includes such an arrangement.

It should be apparent that various details of construction and combinations can be utilized Without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

1. A strainer bag of felt having a substantially cylindrical upper portion with an open upper end, a slightly convex lower portion, a vertical seam in said upper portion extending to said covex lower portion, said lower portion having a seam extending from the side edges adjacent the bottom of the cylindrical portion across the lower portion through the apex thereof, said lower portion being so constructed and arranged that a line drawn from the apex to the intersection of the cylindrical and convex portions is between about 32 and 45, said seams being interconnected to form the felt into a unitary strainer bag, and an attachment means surrounding said open end.

References Cited UNITED STATES PATENTS 567,387 9/1896 Hawley 210477 603,323 5/1898 Echart 210489 X 1,028,114 6/1912 Holton 210-474 X 1,284,944 11/1918 St. Pierre 210448 1,809,935 6/1931 Herzmark 210477 X 2,100,951 11/1937 Glass et al. 210460 X 2,286,434 6/1942 Myers et a1. 210489 X 2,416,524 2/1947 Huse et al. 210489 X 3,067,504 12/1962 Lubben et al. 210460 X 3,204,391 9/1965 SchWab 210448 X FOREIGN PATENTS 20,945 10/ 1925 Great Britain.

REUBEN FRIEDMAN, Primary Examiner.

C. M. DITLOW, Assistant Examiner.

US. Cl. X.R. 

